Airplane



f 23, 1945. H. T. NAGAMATSU AIRPLANE Filed May 19, 1945 INVENTOR HENRY I NAGAMATSU ATTORNEY n p is takento overcome the situation.

Patented Oct. 23, 1945 UNITED STATES PATENT OFFICE AIRPLANE Henry T. Nagamatsu, Cheektowaga, N. Y., assign- .or to Cnrtiss-Wright Corporation, a corporation of Delaware Application May 19, 1943, Serial No. 487,835

Claims. (Cl. 2244-40) This invention relates to airplanes and more particularly to the control surfaces therefor.

With some airplanes there is a tendency for the rudder to become easily locked when angled to. large angles as when the airplane is being sideslipped into an airport. The air flow becomes separated from the vertical stabilizer on jtheface opposite the direction into which the airplane is being forced and as a. result pressure on the controls becomes such that the pilot is unable to cope with the same, the rudder thereby becomes locked, and the airplane gets completely out of control unless some immediate step One known way of overcoming the situation is to speed up the propeller to provide more air over the suriaceabut this is not practicalat times of land- U ing.

Itis, therefore. the object of thepresent invention to provide means which will automatically come into play as the airplane is angled to positively insure a flow oi air over the stabilizer face opposite to the face receiving the major flow of the air.

It is another object of the invention to prorudder to lock which is of simple construction plane isangled about its centerof gravity to one sidelor theother, certain of the slots are so presented that air is taken in through the slot and delivered to the opposite side of the stabilizer and directed to the rudder face on that side of the stabilizer. In this fashion the air pressure on the opposite side of the rudder is increased and the difierential of pressure between the two sides of the rudder is accordingly reduced; Should the airplane be turned and yawed in the opposite direction, the other slots entering from that side. of the stabilizer will automatically come into play and air will bedelivered to one side of the stabilizer. Such air p vide means for overcoming thetendency for the trol of the airplane when being angled in this direction.

For other objects and for a. better understanding of the invention, reference may be had to the ,following detailed description taken in connection with the accompanying drawing, in which Fig. 1 is a perspective view of a vertical stabilizer of an airplane with the nozzle-shaped slots of the present invention extending there through.

Fig. 2 is an elevational view or the tail portion of the airplane with the vertical stabilizer incorporating the features of the present invention thereon.

Fig. 3 is a cross sectional view taken through the stabilizer and rudder and along the line 33'of Fig.2.

Fig. 4 is a diagrammatic view of a stabilizer and rudder and illustrating the path or the air over the same when the airplane is running true to its course.

Fig.5 is a. diagrammatic plan view,oi an airplane in a yawed position about its center of gravity and illustrating the path or the air over the tail surfaces when no slots are employed.

Fig. 6 is an enlarged diagrammatic view of the tail surfaces when the airplane is angled in the position shown in Fig. 5 and showing the manner in which the air is received by the slots provided according to the present invention and delivered to the opposite side of the stabilizer and to the rudder.

Referring now particularly to Figs. 1, 2, and

nected a. rudder 13 adapted to pivot about a vertical axis thereon.

When the airplane II is angled about its center of gravity to the position shown in Fig. 5, the air flow over the vertical stabilizer is such that separation of the air on the face "of the stabilizer opposite to the face being presented to the air flow, is separated at a point I I and considerable turbulence l5 of the air from then on out to the end of the rudder takes place. This turbulence reduces considerably the amount of air pressure on thatside of the rudder, thereby causing the rudder to be swung further to the right and out on control of the pilot.

is distributed over the rudder face on the latter side 01' the airplane and the pilot is given con- In order'to ziltfthis situation, therhas been provided, according to the present invention, a nozzleor funnel-shaped slot I! extending irom one side of the stabilizer to the opposite side thereof in order that the air may be directed thereover as indicated by the arrows l8, to the rudder. By means of this slot, sufficient air may be maintained on the opposite side of the stabilizer such that the flow thereof may not separate and whereby a balancing force will be provided on the rudder. This. slot ll being of nozzleshape has a large entrance I!) and a small outlet 20, whereby the velocity of the air leaving the slot is increased and will be greater than the velocity of the air entering at [9.

When the airplane is angled in an opposite direction to that shown in Fig. 5, another slot 2| will come into play. This slot 2| is identical in shape to the slot l1 and-the air is similarly distributed to the opposite face of the stabilizer and acts upon the rudder on that side thereof in the same manner. These slots 21 are altermated with the slots H to provide pairs, one above the other, and throughout the height of the stabilizer there are two pairs of these slots. It will be apparent that operating mechanism incorporating movable parts is not necessary in order to present these slots to the air flow to receive the air, and that the operation of the same is entirely automatic, one of the slots of a pair coming into play when the airplane is angled to one direction and the other slots of a pair coming into play when the airplane is angled in the opposite direction. The slots [1 and 2| are preferably located in the stabilizer between ribs 22 and forwardly of a spar 23.

These slots may be formed in the stabilizer in any manner which may seem practical to the designer. One such means which can be applied to a completed airplane without great difiiculty would be the insertion of a plastic member hollowed out toprovide a nozzle opening therethrough and adapted to be fitted into prepared openings cut into the faces of the stabilizer.

While various changes may be made in the detailed construction, it shall be understood that such changes shall be made within the spirit and scope of the present invention as defined by the appended claims.

I claim as my invention:

1. In an airplane, a fuselage having a tail section, a vertical stabilizer carried by said tail section, a rudder hingedly connected to the trailing edge of said stabilizer, and a plurality of slots formed in said stabilizer adjacent the leading edge thereof and each extending between an entrance and anexit which are located at opposite sides of said leading edge, at least one of said slots having an entrance at one side of said leading edge and at least one other of said slots having an entrance at the opposite side, said slots being inclined from their entrances to said exits generally in the direction of said rudder so that at least one of said slots will receive air and deliver it to the low-pressure side of said rudder regardless of the angular direction of yaw, whereby to counteract rudder lock.

2. In an airplane, a fuselage having a tail section, a vertical stabilizer carried by said tail section, a rudder hingedly connected to the trailing edge of said stabilizer, and a plurality of slots formed in said stabilizer adjacent the leading edge thereof and each extending between an entrance and an exit which are located at opposite sides of said leading edge, alternate of said entrances being located at one side of said leading edge and the intermediate entrances being located at the opposite side of said leading edge, said slots being inclined from their entrances to their exits in the direction of said rudder so that certain of said slots will receive air and deliver it to the low-pressure side of said rudder regardless of the angular direction of jaw, whereby to counteract rudder lock.

3. In an airplane, a fuselage having a tail section, a vertical stabilizer carried by said tail section, a rudder hingedly connected to the trailing edge of said stabilizer, and a plurality of slots formed in said stabilizer adjacent the leading edge thereof, each of said slots extending between an entrance and an exit which are located at opposite sides of said leading edge and tapering from the entrances in the direction of the exits, at least one of said slots having an entrance at one side of said leading edge and at least one other of said slots having an entrance at the opposite side, said slots being inclined from their entrances to said exits generally in the direction of said rudder so that at least one of said slots will receive air and deliver it to the low-pressure side of said rudder regardless of the angular direction of yaw, whereby to counteract rudder lock.

4. In an airplane, a fuselage having a tail section, a vertical stabilizer carried by said tail section, a rudder hingedly connected to the trailing edge of said stabilizer, and a plurality of slots formed in said stabilizer adjacent the leading edge thereof, each of said slots extending between an entrance and an exit which are located at opposite sides of said leading edge and tapering from the entrances in the direction of the exits, alternate of said entrances being located at one side of said leading edge and the intermediate entrances being located at the opposite side of said leading edge, said slots being inclined from their entrances to their exits in the direction of said rudder so that certain of said slots will receive air and deliver it to the low-pressure side of said rudder regardless of the angular direction of yaw, whereby to counteract rudder lock.

5. In an airplane, a fuselage having a tail section, a stabilizer carried by said tail section, a control surface hingedl connected to the trailing edge of said stabilizer, and a plurality of slots formed in said stabilizer adjacent the leading edge thereof and each extending between an entrance and an exit which are located at opposite sides of said leading edge, at least one of said slots having an entrance at one side of said leading edge and at least one other of said slots having an entrance at theopposite side, said slots being inclined from their entrances to said exits generally in the direction of said control surface so that at least one of said slots will receive air and deliver it to the low-pressure side of said control surface regardless of the angular direction of yaw, whereby to counteract control surface lock.

HENRY T. NAGAMATSU. 

